4-AO 0-10V extension does not bring 0-10V on all ports

  • Hi,

    i am using a 4-AO 0-10V extension and i use 24V DC as AOV on all Ports.
    If i now set 100% to all of the AO, i can measue on 2 ports 10V (like it should
    be), but on 1 Port 24V and on the other 21V. These 2 faulty output voltages do also
    not change, if i change the board trimmer.

    best regards,

  • By the way, could it be, that CH0 and CH1 are interchanged.
    It i write adress 200 on the pca9685 then CH1 is set not CH0.
    CH2 and CH3 are set correctly. Or is it a problem with my
    extension board ?

    best regards,

  • And you had from the beginning correct wiring?

    Because the output should not be higher than the voltage value of 10.5V.

    From what you describe is a board defective.

  • Hi Pablo,

    i thoiught i had the correct cabeling from the beginning, but i was not sure.
    So i ordered 2 more 4-AO 0-10V extensions and got them last week.
    I double checked everything and test every AO-Port and everything worked
    as excepted. It run's like a charm for 4 days ... until now.
    The same effect occurs again, but now 3 ports of the extension does not
    work anymore. 2 of them show on Analog-Out 24 V all the time. 1 shows
    always 0V. The 4. port still work's.
    As i got the same problem with the 2nd extension board, i don't think, that
    i made a fault on the first extension board.

    Because i used the UniPI with the extension for control heating , i now run
    into big problems because of the not working extension.

  • Hi,
    in that case a have a question about sources. What is your power supply for the outputs.
    And are these connected individually, or in common. I have idea, that after some time the power supply exeeds the limit of the AO... Maybe?
    Second question, what did you connect to the outputs? You are talking about heating.
    Maybe better link to technical docummentation of the devices.

  • Hi,

    power supply is 24V DC, connected in common. I thought the limit is 36 V ...

    i connected 2 actuators, which have an 0-10V input and runs with 24V AC,
    Model Honeywell M7410E1002 and M7410E1028

    best regards

  • Hi,

    of course that limit is 36V, if linearity is guaranteed, because your devices are typical for these board.

    We can try measuring on board. When you have 5V behind 7805, we can exclude a mistake on supply.

    If you have voltmeter with measuring duty cycle, try it on inputs and ouptputs of optrons, whether it working corectly.

    And finally, when there is on on fifth pin of the operation amplifier (IC 1;3;5;7) half of the configured output voltage, it is OK.

  • @Pablo

    i will send it back to you ...

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